PubMed · 2026-05-11
Researchers tested two specific strains of soil-dwelling cyanobacteria as natural fertilizers for lettuce and found they work very differently from each other — one boosts leafy growth and loads plants with nitrogen and iron, while the other enriches the soil with potassium and manganese. The study is strong evidence that swapping chemical fertilizers for living microbial ones requires choosing the right strain for the right job.
Microcoleus sp. LC_M4 produced significantly more of a natural plant growth hormone (IAA), resulting in higher lettuce fresh weight and more leaves compared to controls and even cow manure treatments.
Microcoleus-treated lettuce had the highest concentrations of nitrogen (5.047%), potassium (90 mg/g), iron (0.564 mg/g), and zinc (156 mg/kg) among all treatments.
The two cyanobacterial strains enriched entirely different soil nutrients — Microcoleus boosted soil nitrogen, iron, phosphorus, and total carbon, while Nodosilinea improved soil potassium, manganese, and zinc — confirming strain-specific effects rather than a general 'biofertilizer' benefit.
